Shallow water arming mechanism

ABSTRACT

A safing and arming device for arming a weapon in the presence of water including a pair of fluidly couplable impellers housed within a chamber which, when the device is immersed, becomes filled with water. Upon rotation of the first impeller by a conventional electric motor, the second impeller, positioned parallel to and beneath the first impeller, is caused to rotate by fluid momentum. Rotation of the second impeller simultaneously positions an explosive element to complete an explosive train and closes a firing circuit. If the chamber contains only air, rotation of the first impeller will not cause the second impeller to rotate and the weapon does not become armed.

1451 Apr. 10, 1973 1 SHALLOW WATER ARMING MECHANISM [75] Inventor: Henderson W. Wright, Ellicott City,

[73] Assignee: The United States of America as represented by the Secretary of the Navy 221 Filed: Nov. 26, 1971 21 Appl. No.: 203,113

[52] US. Cl ..102/l6, 102/70.2 G [51] Int. Cl. ..F42b 21/34, F42b 5/08 [58] Field of Search ..l02/7, l0, l3, 14,

102/16, 18, 17, 70 R, 70.2 R, 70.2 G, 70.2 GA; 114/20 R, 21 R [56] References Cited UNITED STATES PATENTS 2,617,703 1l/1952 Minkler ..114/20 R X 2,645,180 7/1953 Stockard 102/17 2,779,217 l/l957 Smith 102/16 2,961,961 11/1960 Kendall et al. 102/17 2,985,105 5/1961 Rabinow et al.... ....102/70.2G 2,989,921 6/1961 Leonard et al. ..l02/l 8 3,170,403 2/1965 Heilprin ..l02/70.2 G

Primary Examiner-Benjamin A. Borchelt Assistant ExaminerJames M. Hanley AttorneyR. S. Sciascia et a1.

[5 7] ABSTRACT A safing and arming device for arming a weapon in the presence of water including a pair of fluidly couplable impellers housed within a chamber which, when the device is immersed, becomes filled with water. Upon rotation of the first impeller by a conventional electric motor, the second impeller, positioned parallel to and beneath the first impeller, is caused to rotate by fluid momentum. Rotation of the second impeller simultaneously positions an explosive element to complete an explosive train and closes a firing circuit. If the chamber contains only air, rotation of the first impeller will not cause the second impeller to rotate and the weapon does not become armed.

6 Claims, 2 Drawing Figures FIRING VOLTAGE FROM FIRING DEVICE BOOSTER PATENTEU R 1 01975 FIRING VOLTAGE FROM FIRING DEVICE BOOSTER FEG.E.

ATTORNEYS SHALLOW WATER ARMING MECHANISM BACKGROUND OF THE INVENTION This invention relates generally to an underwater weapon safing and arming device, and more particularly to a safing and arming device which is capable of arming an underwater weapon in shallow water independent of hydrostatic pressure.

In the use of underwater weapons, such for example as mines, it is desirable to render the firing mechanism inactive at all times prior to water entry. This is considered advantageous in order to assure that the weapon is not prematurely actuated, for example, during handling.

Several diverse arrangements have been heretofore proposed and use to provide anning of a firing circuit only after water entry. One widely used arming device relies upon the use of hydrostatic pressure to operate either a piston of a diaphragm. The piston or diaphragm usually causes the repositioning of an outof-line explosive element in an explosive train or various switching operations to cause the arming of a firing circuit. One severe limitation of hydrostatic responsive apparatus, however, is that in most cases large hydrostatic pressures, present only at great depths, are necessary for successful operation thereof. This requirement often precluded weapons from employing such arming devices when such weapons were to be used in a shallow water environment. In cases where the hydrostatic responsive apparatus was designed to have sufficient sensitivity to operate in shallow water, premature initiation due to changes in atmospheric pressure occurring during storage, handling and as a result of ordinary temperature changes have often occurred. Further, the tolerances required for shallow water operation are often so close that only a slight variation in machining might cause a malfunction in operation.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a new and improved safing and arming device for use in an underwater weapon.

Another object of this invention is the provision of a new and improved safmg and arming device for use in shallow water environments.

Still another object of the present invention is to provide a new and improved shallow water safing and arming device whose operation does not depend upon hydrostatic pressure.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by providing in an underwater weapon, a saf'mg and arming device including a first motor driven impeller communicating with a second impeller in a manner whereby when the device is in a water environment, rotation of the first impeller induces rotation of the second impeller, whereas in an air environment such coupling does not exist. The second impeller is mechanically connected to a plurality of switches in a firing circuit and an explosive train, the circuit and train normally being in a safe mode. Upon rotation of the second impeller, occurring only when the device is in a water environment, both the switches and the explosive train are caused to attain an armed condition. Upon receipt of a firing voltage from an external firing device, the weapon is caused to be initiated.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendent advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed descriptions when considered in connection with the accompanying drawings wherein:

FIG. 1 is a diagrammatic view of the safing and arming device in its safe condition according to the present invention; and

FIG. 2 is a view taken along line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, the safing and arming device of the present invention is shown as comprising a housing 10 enclosing an impeller assembly 12, operably connected to an electroresponsive explosive train assembly 14 and a switch closing element 16. A mechanical gear assembly 18 is provided to mechanically couple the switch closing element 16 and explosive train 14 to the impeller assembly 12 as will be described in greater detail hereinafter.

The impeller assembly 12 includes a first impeller 20 rotatably mounted within housing 10. Passages 22 and 24 are formed in housing 10 in order to provide fluid communication between first impeller 20 and the external environment. Such communication is normally prevented by a cup-shaped cap 26 having on O-ring 28 provided on the interior surface thereof overlying both passages. A conventional electric motor 30 is provided to rotatably drive a shaft connected to first impeller 20.

Referring to FIG. 2, a second impeller 32 is rotatably mounted substantially subjacent to and in the plane of first impeller 20. Fluid communicating passages 34 comprise a fluid chamber and are provided to fluidly couple the two impellers in a manner to be described. Second impeller 32 is of a larger diameter and has a greater number of buckets 35 than does first impeller 20.

Rigidly connected to and rotatable with second impeller 32 is a cylindrical shaft 36 having a pinion 38 attached thereto. A second shaft 40 is mechanically coupled to first shaft 36 through gear 42 which meshes with pinion 38.

The explosive train assembly 14 includes an electroresponsive squib 44 separated from an explosive booster charge 46 by a normally out-of-line rotatably mounted explosive filled element 48 connected to shaft 430 (shown out-of-line in FIG. 1). Alternatively, booster charge 46 and explosive element 48 may be combined as a single explosive charge connected to shaft 40 and rotatable therewith, to be positioned in line with squib 44 and to be detonated thereby upon completion and activation of the firing circuit as more fully described hereinbelow. The explosive train assembly 14 is electrically coupled to a firing device (not shown) located externally to the arming device usually in another section of the weapon. The electrical circuit, however, is provided to be normally open and short circuited in order to prevent a premature initiation of the squib 44 due to any inadvertent increase in voltage. In

the present embodiment, this is accomplished by a normally open switch 50 which provides the circuit to be in an open mode and normally closed switch 52 which maintains a short circuit. The switch initiation element 16 is mechanically coupled to shaft 40 and is of conventional construction such that, upon rotation of shaft 40, switches 50 and 52 are closed and opened respectively. A third normally closed switch 54 is provided in a second external electrical circuit for providing energy to motor 30. Switch 54 is adapted to open upon rotation of shaft 40 in a similar manner to switch 52.

In operation of the device, Cap 26 is first removed, thereby opening passages 22 and 24 to the external environment. A switch 56 is then closed completing the motor energizing circuit thereby causing first impeller 20 to begin rotation in a direction shown in FIG. 2. A battery 58 may be of the water-actuatable type thereby obviating the need for switch 56, or to provide a safety feature. Prior to submersion within water, the impeller chamber 34 is filled with air. Consequently, rotation of nection between pinion 38 and gear 42. The rotation of shaft 40 causes two things to occur substantially simultaneously. First, the switch initiating element 16 is operated thereby causing switch 50 to close and switch 52 to open thereby arming the firing circuit enabling initiation of squib 44 should a firing voltage be present. Secondly, the rotation of shaft 40 causes the out-of-line explosive element 48 to be rotated to an in-line position thereby completing the explosive train in a manner to allow actuation thereof as described hereinabove upon initiation of squib 44. Further, element 16 causes switch 54 to open thereby opening the motor energizing circuit thereby causing the first impeller 20 to cease rotation. Both the switch initiating element 16 and explosive train assembly 14 are of conventional structure and the construction of each forms no part of the present invention.

It should be noted that the gear train assembly comprising shafts 36 and 40 and gears 38 and 42 serve a multiple purpose. It serves as an inertia element preventing rotation of the shaft during handling and storage of the mechanism; it amplifies the torque produced by the impellers to a sufficient level for the operation described to be performed; and, finally, it provides an interval delay timing function in the duration of the total arming sequence.

Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. For example, the apparatus described herein is directed to two impellers in the same plane with their shaft axis parallel. It is conceivable that other shafts relationships and impeller configurations are attainable. It is further possible to use the water sensing ability of the present invention in other applications such, for example, for interrupting a power train which is required to operate only when water is present. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A safing and arming device for arming a firing system of a weapon a predetermined time after said weapon is immersed in water comprising:

an electric motor,

a motor shaft coupled to and adapted to be driven in a rotory motion by said motor;

impeller means for fluidly transmitting said rotory motion from said motor shaft to a first shaft, operable only when said device is immersed in water;

means permitting access of water to said impeller means; and

an explosive train including an electroresponsive squib electrically coupled to an external firing circuit and a normally out-of-line explosive element coupled to said first shaft and adapted to be positioned in line with said squib upon rotation of said first shaft through a predetermined angle.

2. A safing and arming device as recited in claim 1 wherein:

said electroresponsive squib is electrically coupled to said external firing circuit by an electric circuit including a first normally open switch which normally prevents the premature initiation of said squib;

said first normally open switch coupled to said first shaft and adapted to close upon rotation of said first shaft through said predetermined angle.

3. A safing and arming device as recited in claim 2 wherein said electric motor is actuated through an electric circuit including a water-actuated battery and a first normally closed switch, said first closed switch coupled to said first shaft and adapted to open upon rotation of said first shaft through a predetermined distance.

4. A safing and arming device as recited in claim 3 wherein said impeller means includes:

a first impeller connected to said motor shaft and rotatable therewith, said first impeller positioned adjacent to at least one passage communicating with the external environment;

a second rotatably mounted impeller having an axis of rotation parallel to the axis of rotation of said first impeller and positioned substantially subjacent thereto, said second impeller connected to said first shaft; and

an impeller chamber fluidly coupling said first impeller to said second impeller.

5. A safing and arming device as recited in claim 4 wherein said first shaft is connected to a pinion which engages a gear connected to a second shaft which is connected to said first closed and first open switch and to said normally out-of-line explosive element.

6. A safing and arming device as recited in claim 1 wherein said explosive train further comprises an explosive charge positioned in line with said squib whereby upon rotation of said first shaft said explosive element is positioned in line between said squib and said explosive charge. 

1. A safing and arming device for arming a firing system of a weapon a predetermined time after said weapon is immersed in water comprising: an electric motor, a motor shaft coupled to and adapted to be driven in a rotory motion by said motor; impeller means for fluidly transmitting said rotory motion from said motor shaft to a first shaft, operable only when said device is immersed in water; means permitting access of water to said impeller means; anD an explosive train including an electroresponsive squib electrically coupled to an external firing circuit and a normally out-of-line explosive element coupled to said first shaft and adapted to be positioned in line with said squib upon rotation of said first shaft through a predetermined angle.
 2. A safing and arming device as recited in claim 1 wherein: said electroresponsive squib is electrically coupled to said external firing circuit by an electric circuit including a first normally open switch which normally prevents the premature initiation of said squib; said first normally open switch coupled to said first shaft and adapted to close upon rotation of said first shaft through said predetermined angle.
 3. A safing and arming device as recited in claim 2 wherein said electric motor is actuated through an electric circuit including a water-actuated battery and a first normally closed switch, said first closed switch coupled to said first shaft and adapted to open upon rotation of said first shaft through a predetermined distance.
 4. A safing and arming device as recited in claim 3 wherein said impeller means includes: a first impeller connected to said motor shaft and rotatable therewith, said first impeller positioned adjacent to at least one passage communicating with the external environment; a second rotatably mounted impeller having an axis of rotation parallel to the axis of rotation of said first impeller and positioned substantially subjacent thereto, said second impeller connected to said first shaft; and an impeller chamber fluidly coupling said first impeller to said second impeller.
 5. A safing and arming device as recited in claim 4 wherein said first shaft is connected to a pinion which engages a gear connected to a second shaft which is connected to said first closed and first open switch and to said normally out-of-line explosive element.
 6. A safing and arming device as recited in claim 1 wherein said explosive train further comprises an explosive charge positioned in line with said squib whereby upon rotation of said first shaft said explosive element is positioned in line between said squib and said explosive charge. 